<?php

namespace weixin;

use think\Db;
use think\Config;
use think\Session;
use think\Request;

/**
 * PKCS7Encoder class
 *
 * 提供基于PKCS7算法的加解密接口.
 */
class PKCS7Encoder {

    public static $block_size = 16;

    /**
     * 对需要加密的明文进行填充补位
     * @param $text 需要进行填充补位操作的明文
     * @return 补齐明文字符串
     */
    function encode($text) {
        $block_size = PKCS7Encoder::$block_size;
        $text_length = strlen($text);
        //计算需要填充的位数
        $amount_to_pad = PKCS7Encoder::$block_size - ( $text_length % PKCS7Encoder::$block_size );
        if ($amount_to_pad == 0) {
            $amount_to_pad = PKCS7Encoder::block_size;
        }
        //获得补位所用的字符
        $pad_chr = chr($amount_to_pad);
        $tmp = "";
        for ($index = 0; $index < $amount_to_pad; $index++) {
            $tmp .= $pad_chr;
        }
        return $text . $tmp;
    }

    /**
     * 对解密后的明文进行补位删除
     * @param decrypted 解密后的明文
     * @return 删除填充补位后的明文
     */
    function decode($text) {

        $pad = ord(substr($text, -1));
        if ($pad < 1 || $pad > 32) {
            $pad = 0;
        }
        return substr($text, 0, (strlen($text) - $pad));
    }

}

/**
 * Prpcrypt class
 *
 *
 */
class Prpcrypt {

    public $key;

    function __construct($k) {
        $this->key = $k;
    }

    /**
     * 对密文进行解密
     * @param string $aesCipher 需要解密的密文
     * @param string $aesIV 解密的初始向量
     * @return string 解密得到的明文
     */
    public function decrypt($aesCipher, $aesIV) {

        try {

            $module = mcrypt_module_open(MCRYPT_RIJNDAEL_128, '', MCRYPT_MODE_CBC, '');

            mcrypt_generic_init($module, $this->key, $aesIV);

            //解密
            $decrypted = mdecrypt_generic($module, $aesCipher);
            mcrypt_generic_deinit($module);
            mcrypt_module_close($module);
        } catch (Exception $e) {
            return array(ErrorCode::$IllegalBuffer, null);
        }


        try {
            //去除补位字符
            $pkc_encoder = new PKCS7Encoder;
            $result = $pkc_encoder->decode($decrypted);
        } catch (Exception $e) {
            //print $e;
            return array(ErrorCode::$IllegalBuffer, null);
        }
        return array(0, $result);
    }

}

/**
 * error code 说明.
 * <ul>

 *    <li>-41001: encodingAesKey 非法</li>
 *    <li>-41003: aes 解密失败</li>
 *    <li>-41004: 解密后得到的buffer非法</li>
 *    <li>-41005: base64加密失败</li>
 *    <li>-41016: base64解密失败</li>
 * </ul>
 */
class ErrorCode {

    public static $OK = 0;
    public static $IllegalAesKey = -41001;
    public static $IllegalIv = -41002;
    public static $IllegalBuffer = -41003;
    public static $DecodeBase64Error = -41004;

}

class WXBizDataCrypt {

    private $appid;
    private $sessionKey;

    /**
     * 构造函数
     * @param $sessionKey string 用户在小程序登录后获取的会话密钥
     * @param $appid string 小程序的appid
     */
    public function __construct() {
//        $appid, $sessionKey
//        $this->sessionKey = $sessionKey;
//        $this->appid = $appid;
    }
    
    public function getSessionKey($sessionKey){
        $this->sessionKey = $sessionKey;
    }
    
    public function getAppID($appid){
        $this->appid = $appid;
    }

    /**
     * 检验数据的真实性，并且获取解密后的明文.
     * @param $encryptedData string 加密的用户数据
     * @param $iv string 与用户数据一同返回的初始向量
     * @param $data string 解密后的原文
     *
     * @return int 成功0，失败返回对应的错误码
     */
    public function decryptData($encryptedData, $iv, &$data) {
        if (strlen($this->sessionKey) != 24) {
            return ErrorCode::$IllegalAesKey;
        }
        $aesKey = base64_decode($this->sessionKey);


        if (strlen($iv) != 24) {
            return ErrorCode::$IllegalIv;
        }
        $aesIV = base64_decode($iv);

        $aesCipher = base64_decode($encryptedData);

        $pc = new Prpcrypt($aesKey);
        $result = $pc->decrypt($aesCipher, $aesIV);

        if ($result[0] != 0) {
            return $result[0];
        }

        $dataObj = json_decode($result[1]);
        if ($dataObj == NULL) {
            return ErrorCode::$IllegalBuffer;
        }
        if ($dataObj->watermark->appid != $this->appid) {
            return ErrorCode::$IllegalBuffer;
        }
        $data = $result[1];
        return ErrorCode::$OK;
    }


    /**
    * 微信信息解密
    * @param  string  $appid  小程序id
    * @param  string  $sessionKey 小程序密钥
    * @param  string  $encryptedData 在小程序中获取的encryptedData
    * @param  string  $iv 在小程序中获取的iv
    * @return array 解密后的数组
    */
   public function decryptData1($appid, $sessionKey, $encryptedData, $iv) {
       $OK = 0;
       $IllegalAesKey = -41001;
       $IllegalIv = -41002;
       $IllegalBuffer = -41003;
       $DecodeBase64Error = -41004;

       if (strlen($sessionKey) != 24) {
           return $IllegalAesKey;
       }
       $aesKey = base64_decode($sessionKey);

       if (strlen($iv) != 24) {
           return $IllegalIv;
       }
       $aesIV = base64_decode($iv);

       $aesCipher = base64_decode($encryptedData);

       $result = openssl_decrypt($aesCipher, "AES-128-CBC", $aesKey, 1, $aesIV);
       $dataObj = json_decode($result);
       if ($dataObj == NULL) {
           return $IllegalBuffer;
       }
       if ($dataObj->watermark->appid != $appid) {
           return $DecodeBase64Error;
       }
       $data = json_decode($result, true);

       return $data;
   }
}
